PLAN B analog blog

All,

I have come upon two resistor value changes which have 
increased the tracking of the Model 15 VCO from 5 to seven plus 
octaves into the 1v/oct input.  All units shipped after today will 
have this change incorporated.

Those of you who have received VCOs who would prefer to have 
this chyange made  - you've got two options:  I would prefer you 
send them to me if at all possible.  If you can't adfford the 
downtime (it will be about a week turnaround) and if you're 
confident with a soldering iron - change the value of  R18 and 
R19 both to 4.7k at 1%.  Currently they are both 2.99K 1%.

Those who want this change done here, please contact me 
offline for my mailing address.

Please note - this change only effects the tracking of the 1v/oct 
input.  All other operations, most important, the two scalable VC 
Inputs and the FM input are uneffected.

This change brings the transistors in the core to their linear 
swee tspot and in so doing, keeps the entore oscillating range in 
this all-inoortant linear range  -WAY past 3k  where most 
sawtoosh core VCOs start to see problems.

- P

All,

I've been asked to clarify the rework instructions for the two 4.7K 15
resistors.  

Again, PLEASE -  at all costs, let me do this for you.  But if you can't to
that, the rework is terribly easy.:

 R18 and R19 are right next to each other at the edge of the board, about 2
inches back form the Frequency pot and about an inch north of the Expo
boardlette that sticks up from the main board down by thepower connector..
You can't miss them.  Currently they ar 2.99k - color bands RED YELLOW WHITE
BROWN BROWN and have a baby blue component body.

Simply desolder these two and replace with 4.7k 1% resistors at the same two
locations.  You will have to recalibrate your 1v/octave scaling after this
is completed. - also quite easy.  I will have a couple of midi files on
this site for download which will assist you to cal your scaling to 7
octaves.

- P

All,
 
I've made some resistor value substitutions to the Model 15 VCO core which
has increased its 1v/oct tracking to over seven octaves.

You may hear as sample of this in a sound file which was recorded from the
Model 15  which will ship to Phil Hendricks early next week.  To hear this,
click on the link below and scroll to NEWS FLASH, which will give a
description of the changes along with an audio sample, as well as the midi
file used to produce it so you can try it at home on your own VCO!

Go here:

http://www.buzzclick-music.com/model_15.html


- P

great news about the improved tracking of the vco15 :-)
i'm biting my tongue until i got mine, can't wait to
get these gorgeous sounding masterpieces.

best wishes

ingo




--- In PLAN_B_analog_blog@yahoogroups.com, Peter Grenader 
<peter@b...> wrote:
> All,
>  
> I've made some resistor value substitutions to the Model 15 VCO 
core which
> has increased its 1v/oct tracking to over seven octaves.
> 
> You may hear as sample of this in a sound file which was recorded 
from the
> Model 15  which will ship to Phil Hendricks early next week.  To 
hear this,
> click on the link below and scroll to NEWS FLASH, which will give a
> description of the changes along with an audio sample, as well as 
the midi

> file used to produce it so you can try it at home on your own VCO!
> 
> Go here:
> 
> http://www.buzzclick-music.com/model_15.html
> 
> 
> - P